Method and apparatus for mechanochemical polishing

Abstract

In a mechanochemical polishing apparatus, a SiC wafer is held on a wafer holding table. The surface of the wafer to be polished is pressed against a polishing cloth applied to a polishing platen with a predetermined processing pressure. The wafer holding table and polishing platen are then rotated to perform polishing with chemical liquid dropped on the polishing cloth. The chemical liquid includes chromium (III) oxide as abrasive grains and hydrogen peroxide water (oxidizing agent) for improving polishing efficiency.

What is claimed is:  
     
       1. A method for mechanochemical polishing, comprising: 
       preparing a chemical solution that includes hydrogen peroxide water and abrasive grains made of chromium (III) oxide;  
       polishing a surface of a SiC wafer by mechanochemical polishing to remove SiC from the surface of the wafer using the chemical solution and a polishing cloth with a processing pressure having a range of approximately 0.1-3.0 kgf/cm 2 ; and  
       increasing oxygen concentration on the surface of the SiC wafer to promote the formation of an oxide of the SiC wafer by performing the polishing in the presence of the hydrogen peroxide water, wherein the oxide of the SiC wafer is formed by catalysis of the chromium (III) oxide, and the oxygen concentration around the polishing surface of the SiC wafer is increased by supplying the hydrogen peroxide water to the polishing surface to promote the formation of the oxide of the SiC wafer.  
     
     
       2. The method according to  claim 1 , wherein the method further includes coating the cloth with grains of manganese dioxide. 
     
     
       3. The method according to  claim 1 , wherein the method includes dropping the chemical solution onto the polishing cloth on the surface of the SiC wafer. 
     
     
       4. The method according to  claim 1 , wherein the method includes adding a solid powder oxidizing agent to the chemical solution. 
     
     
       5. The method according to  claim 4 , wherein the solid powder includes at least one of manganese dioxide and dimanganese trioxide. 
     
     
       6. The method according to  claim 4 , wherein the method includes polishing the surface of the semiconductor wafer on a member that moves relatively to the semiconductor wafer, wherein the solid powder is located on the member. 
     
     
       7. The method according to  claim 4 , wherein the method includes dropping the chemical solution, in which the solid powder is dispersed, onto the surface of the SiC wafer. 
     
     
       8. The method according to  claim 1 , wherein the method includes supplying a solid powder made of a material other than chromium (III) oxide to the surface of the semiconductor wafer when the surface is polished, wherein the material catalyzes a chemical reaction. 
     
     
       9. The method according to  claim 8 , wherein the method includes dispersing the solid powder in a liquid and dropping the liquid and the powder on the surface of the semiconductor wafer. 
     
     
       10. The method according to  claim 8 , wherein the method includes placing the solid powder on a member that is moved relatively to and contacts the surface of the SiC wafer when the surface is polished. 
     
     
       11. The method according to  claim 8 , wherein the solid powder contains at least one of titanium dioxide, cadmium sulfide, and diindium trioxide. 
     
     
       12. The method according to  claim 8 , wherein the method includes irradiating the solid powder with light when the surface of the semiconductor wafer is polished. 
     
     
       13. The method according to  claim 1 , wherein the method includes heating the surface of the semiconductor wafer during the polishing. 
     
     
       14. The method according to  claim 1 , wherein the polishing cloth is comprised of suede. 
     
     
       15. The method according to  claim 1 , further comprising increasing the oxygen concentration reacting with the SiC wafer during the increasing of the oxygen concentration on the surface of the SiC wafer. 
     
     
       16. The method according to  claim 1 , wherein the abrasive gains have a gain size of 5 μm or less. 
     
     
       17. The method according to  claim 1 , wherein the polishing is performed for 10 minutes or more when the processing pressure is in a range of 0.6-3.0 kgf/cm 2 .